1. Field of the Invention
The present invention generally relates to wireless local area networks. More particularly, the present invention relates to measuring the throughput of transmissions over wireless local area networks.
2. Description of the Related Art
Computers have traditionally communicated with each other through wired local area networks (“LANs”). However, with the increased demand for mobile computers such as laptops, personal digital assistants, and the like, wireless local area networks (“WLANs”) have developed as a way for computers to communicate with each other through transmissions over a wireless medium using radio signals, infrared signals, and the like.
In order to promote interoperability of WLANs with each other and with wired LANs, the IEEE 802.11 standard was developed as an international standard for WLANs. Generally, the IEEE 802.11 standard was designed to present users with the same interface as an IEEE 802 wired LAN, while allowing data to be transported over a wireless medium.
Although WLANs provide users with increased mobility over wired LANs, the quality of communications over a WLAN can vary for reasons that are not present in wired LANs. For example, everything in the environment can behave as a reflector or attenuator of a transmitted signal. As such, small changes in the position of a computer in a WLAN can affect the quality and strength of a signal sent by the computer and can affect the throughput of signals sent over the WLAN.
In a conventional system, throughput across a WLAN is measured by a computer in the WLAN using an echo request-reply mechanism that uses an OSI layer of layer 3 or above. However, components in a WLAN often cannot support an OSI layer of layer 3 or above or are inconvenient or administratively impractical to configure with an echo reply-request mechanism. Furthermore, processing data at layer 3 or above can add delay, and thus affect the calculated throughput.
Alternatively, a separate device that can support an OSI layer of layer 3 or above can be used with a computer sending transmissions to measure throughput across a WLAN. However, because the separate device is typically placed “behind” an access point receiving transmissions from the computer, the calculated throughput can include the extra path length between the device and access point, as well as delays and the effects of bottlenecks at the access point. Furthermore, processing data at layer 3 or above can add delay, and thus affect the calculated throughput.